Various trapezoidal seal ring connections are known from the prior art for connecting together flow lines or conduits. This arrangement generally includes a male member, a female member and a seal ring. The male member has an end with an inwardly tapered frustoconical exterior surface. The female member has an end with an outwardly tapered frustoconical exterior surface having an angle of taper with respect to the axis of the member that is less than the angle of taper of the end of the male portion. The seal ring is generally trapezoidal in cross section and has an outer surface with an angle of taper substantially equal to that of the inner surface of the female member, and an inner surface having an angle of taper that is substantially equal to the angle of taper of the end of the male member. As the male and female members are urged into mating engagement, as for example, by flanges, the seal ring is wedged tightly therebetween.
Various improvements have been made to the trapezoidal seal ring connection to enhance the proper seating of the seal ring between the mating surfaces of the male and female members. For example, trapezoidal seal rings formed to include a radially extending lip were developed for providing a visual indication of the proper alignment of the parts as the male and female members were urged into engagement. Additional modifications and improvements of the lip which have been developed include spacing of the lip from the female member and sizing of the lip, seal ring, and male and female members relative to each other such that proper axial alignment among the parts is maintained and an adequate seal is achieved. Such modified trapezoidal seal rings having radially outwardly extending lips are described in U.S. Pat. Nos. 4,452,474 and 4,648,632.
One problem which has heretofore not been addressed, as far as applicant is aware, is that the male and female members in such connections are generally spaced apart axially from each other, and the trapezoidal seal ring has a larger inside diameter than a central bore formed through the male and female members for the flow of fluid therein, such that a gap or discontinuity is created in the surface adjacent the flow of the fluid. This gap causes turbulence in the fluid flowing adjacent thereto which can in some applications result in erosion of the central bore in the male and female members in the vicinity of the gap. Accordingly, there is a need for a modification of the trapezoidal seal ring connection of the prior art to avoid the erosion which may be caused by the presence of the discontinuity between the male and female members.